Idea: Infer types / parameters from runtime (V8 debugger/inspector protocol)

[niieani]

Given the new "infer parameters from usage" functionality, it would seem doable to do something similar like "infer parameters from runtime/debugger", especially in environments like VSCode, which tightly integrate a debugger.

In runtime you get most of the information to generate pretty good types, at least for a start, so... why not? This would be a massive help in migrating JavaScript to TypeScript.

Also, V8 has just recently introduced takeTypeProfile to the inspector protocol, that could be used to leverage just that. There's an example usage here: https://github.com/fhinkel/type-profile.

https://github.com/Microsoft/dts-gen attempts to do something like this, although it doesn't integrate with the editor.

[mhegazy]

You can implement some of these features in a language service plugin today. would love to see someone experiment with that.

[weswigham]

dts-gen's functionality is now integrated into the compiler with #26588, so I think we've done this.